Potassium-40 has a half life of 1.251×billion<span> years</span><span>. To determine the percentage potassium-40 remaining after 3.9 billion years, divide
3.9 by 1.251, = 3.12.
This is the number of times the original amount of potassium-40 reduces by 50%. The remaining percentage is therefore 100%/(3.12 * 2) = 16.03%.</span>
Leftover radiation from the big bang is your answer hope i helped
Prophase of mitosis do the chromosomes become distinctly visible in the microscope.
During metaphase, the nucleus dissolves and the cell's chromosomes condense and move together, aligning in the center of the dividing cell. At this stage, the chromosomes are distinguishable when viewed through a microscope. The first stage of mitosis and of meiosis I and II.
During prophase the chromosomes become visible as distinct structures, the nuclear envelope breaks down, and a spindle forms (Meiotic prophase I is more complex, and includes synapsis of homologous chromosomes and crossing over). During Prophase chromosomes become Clearly visible, nuclear envelope disappears, kinetochores and spindle fibers form.
To learn more about prophase , here
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